ASoC: Intel: mfld-pcm: Fix to Store device context in sst_data

Some debug prints use dev context in sst_data. Store the device context for
the same.

Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>